RFR: JDK-8323190: Segfault during deoptimization of C2-compiled code

Wed Jan 10 01:29:40 UTC 2024

Currently, if `ReduceAllocationMerges` reduces an allocation merge that is used as a monitor C2 will SIGFAULT in `Process_OopMap_Node` because it's missing code to handle that case.  This patch fixes C2 to properly handle reduced allocation merges that are used as monitors. 

Tested with Linux x86_64 hotspot_all.

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Commit messages:
 - Fix invalid location.

Changes: https://git.openjdk.org/jdk/pull/17333/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17333&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8323190
  Stats: 88 lines in 2 files changed: 88 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/17333.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17333/head:pull/17333

PR: https://git.openjdk.org/jdk/pull/17333